Oil rose towards $78 a barrel Wednesday, supported by a weaker dollar and gains in stock markets on renewed investor risk appetite as concerns about a euro zone debt crisis subsided. US crude for March delivery rose 43 cents to $77.44 a barrel at 1045 GMT, after closing 3.9 percent higher Tuesday. London Brent crude for April climbed 39 cents to $76.07 a barrel. The euro held near a one-week high against the dollar on a return of risk appetite as global share markets and commodity prices extended gains, although traders were prepared to dump risky assets should more news about Greece's debt woes emerge.